1. Technical Field
The present invention relates to methods for manufacturing a flanged article from a sheet material. More particularly, the present invention relates to methods for manufacturing a flanged article from a sheet material by utilizing a press forming machine.
2. Related Art
A known method for manufacturing a flanged article is taught, for example, by Japanese Laid-open Patent Publication Number 10-202329, in which a toothed recessed plate or ratchet plate for a seat reclining device of a vehicle is exemplified as a flanged article that can be prepared utilizing the known method. In this known art, a disk-like sheet material or sheet blank is placed and clamped between upper and lower dies of a press forming machine. Thereafter, a punch associated with the upper die is lowered by a predetermined distance toward a corresponding die opening defined within the lower die. As a result, the sheet material is press formed or half die cut, to thereby form the ratchet plate that comprises a central depressed body and a peripheral flange. The peripheral flange of the ratchet plate is integrally connected to the central body via an annular shear deformed connecting portion. As a result, the peripheral flange and the central body define a circular open cavity or recess. Further, two tooth forming edges are circumferentially defined on the punch. Therefore, a pair of toothed portions can be formed on the inner circular surface of the peripheral flange when the sheet blank is press formed.
According to this known method, when the sheet material is half die cut by the punch, the sheet material is compressed and deformed along the periphery of the punch. As a result, the compressed sheet material may partly move towards the shear deformed connecting portion due to plastic flow, to thereby prevent the shear deformed connecting portion from cracking. However, the central body will have substantially the same thickness as the peripheral flange, which thickness is substantially equal to the thickness of the sheet material.